Web Distributed Authoring and Versioning (WebDAV) SEARCH

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This document specifies a set of methods, headers, properties and content-types composing WebDAV SEARCH, an application of the HTTP/1.1 protocol to efficiently search for DAV resources based upon a set of client-supplied criteria.¶

This document defines I ↓WebDAVWeb Distributed Authoring and Versioning (WebDAV) SEARCH, an application of HTTP/1.1 forming a lightweight search protocol to transport queries and result sets ↑ I ↓andthat allows clients to make use of server-side search facilities. It is based on the expired draft for ↑ I ↓WebDAV DASLDAV Searching & Locating[DASL]. [DASLREQ] describes the motivation for DASL.¶

DASL will minimize the complexity of clients so as to facilitate widespread deployment of applications capable of utilizing the DASL search mechanisms.¶

An instruction that governs the execution of the query but is not part of the search scope, result record definition, the search criteria, or the sort specification. An example of a search modifier is one that controls how much time the server can spend on the query before giving a response.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT" "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].¶

This document uses XML DTD fragments as a purely notational convention. WebDAV request and response bodies can not be validated due to the specific extensibility rules defined in Section 23 of [RFC2518] and due to the fact that all XML elements defined by this specification use the XML namespace name "DAV:". In particular: ¶

extension attributes (attributes not already defined as valid for this element) may be added anywhere, except when explicitly stated otherwise.

When an XML element type in the "DAV:" namespace is referenced in this document outside of the context of an XML fragment, the string "DAV:" will be prefixed to the element type.¶

Similarily, when an XML element type in the namespace "http://www.w3.org/2001/XMLSchema" is referenced in this document outside of the context of an XML fragment, the string "xs:" will be prefixed to the element type.¶

↑ I ↓Note that this draft currently defines elements and properties in the WebDAV namespace "DAV:" which it shouldn't do as it isn't a work item of the WebDAV working group. The reason for this is the desire for some kind of backward compatibility to the expired DASL drafts and the assumption that the draft may become an official RFC submission of the WebDAV working group at a later point of time. This spefication defines elements, properties and condition names in the XML namespace "DAV:". In general, only specifications authored by IETF working groups are supposed to do this. In this case an exception was made, because WebDAV SEARCH started it's life in the IETF DASL working group (<http://www.webdav.org/dasl/>, and at the time the working group closed down there was already significant deployment of this specification. ¶

The client invokes the SEARCH method on a resource that will perform the search (the search arbiter) and includes a text/xml or application/xml request entity that contains the query.

The search arbiter performs the query.

The search arbiter sends the results of the query back to the client in the response. The server MUST send an entity that matches the ↑ I ↓[RFC2518] PROPFIND responseWebDAV multistatus format ([RFC2518], Section 11).

The client invokes the SEARCH method to initiate a server-side search. The body of the request defines the query. The server MUST emit an entity matching the ↑ I ↓[RFC2518] PROPFIND responseWebDAV multistatus format ([RFC2518], Section 11).¶

The SEARCH method plays the role of transport mechanism for the query and the result set. It does not define the semantics of the query. The type of the query defines the semantics.¶

The Request-URI identifies the search arbiter. Any HTTP resource may function as search arbiter. It is not a new type of resource (in the sense of DAV:resourcetype as defined in ↑ I ↓[RFC2518]Section 13.19 of [RFC2518]), nor does it have to be a WebDAV-compliant resource.¶

The SEARCH method defines no relationship between the arbiter and the scope of the search, rather the particular query grammar used in the query defines the relationship. For example, a query grammar may force the ↑ I ↓rRequest-URI to correspond exactly to the search scope.¶

If a request body with content type text/xml or application/xml is included, it MUST be either a DAV:searchrequest or a DAV:query-schema-discovery XML element. It's single child element identifies the query grammar.

For DAV:searchrequest, the definition of search criteria, the result record, and any other details needed to perform the search depend on the individual search grammar.

For DAV:query-schema-discovery, the semantics is defined in Section 4.

(DAV:search-grammar-discovery-supported): when an XML request body is present and has a DAV:query-schema-discovery document element, the server MUST support the query schema discovery mechanism described in Section 4.

(DAV:search-grammar-supported): when an XML request body is present, the search grammar identified by the document element's child element must be a supported search grammar.

(DAV:search-multiple-scope-supported): if the SEARCH request specified multiple scopes, the server MUST support this optional feature.

(DAV:search-scope-valid): the supplied search scope must be valid. There can be various reasons for a search scope to be invalid, including unsupported URI schemes and communication problems. Servers MAY add [RFC2518] compliant DAV:response elements as content to the condition element indicating the precise reason for the failure.

If the server returns 207 (Multistatus), then the search proceeded successfully and the response MUST↑ I ↓match that of a PROPFINDuse the WebDAV multistatus format ([RFC2518], Section 11). The results of this method SHOULD NOT be cached.¶

There MUST be one DAV:response for each resource that matched the search criteria. For each such response, the DAV:href element contains the URI of the resource, and the response MUST include a DAV:propstat element.¶

Note that for each matching resource found there may be multiple URIs within the search scope mapped to it. In this case, a server SHOULD report I ↓allonly one of these URIs. Clients can use the live property DAV:resource-id defined in ↑ I [BIND]Section 3.1 of [BIND] to identify possible duplicates.¶

A response MAY include more information than PROPFIND defines so long as the extra information does not invalidate the PROPFIND response. Query grammars SHOULD define how the response matches the PROPFIND response.¶

This example demonstrates the request and response framework. The following XML document shows a simple (hypothetical) natural language query. The name of the query element is natural-language-query in the XML namespace "http://example.com/foo". The actual query is "Find the locations of good Thai restaurants in Los Angeles". For this hypothetical query, the arbiter returns two properties for each selected resource.¶

A server MAY limit the number of resources in a reply, for example to limit the amount of resources expended in processing a query. If it does so, the reply MUST use status code 207, return a DAV:multistatus response body and indicate a status of 507 (Insufficient Storage) for the search arbiter URI. It SHOULD include the partial results.¶

I believe the same response body that
contains the first N <DAV:response> elements should also contain a
*different* element stating that the results were incomplete and the result
set was truncated by the server.
There may also be a need to report that the results were incomplete and the
result set was truncated at the choice of the client (isn't there a limit
set in the client request?) That's important so the client knows the
difference between receiving 10 results because there were >10 but only 10
were asked for, and receiving 10 results because there were only exactly 10
results and it just happens that 10 were asked for.

I agree that this could be useful, but I think this issue should be
consolidated with issue JW5 (see below), which proposes that DASL
basicsearch ought to have a way for client to request additional result
sets. It should be moved because there is little or no value in allowing a
client to distinguish between the case where "N results were requested, and
there are exactly N available" and "N results were requested, and there are
more than N available" if there is no way for client to get the next batch
of results.

Feedback from interim WG meeting: agreement that marshalling should be
rewritten and backwards compatibility is not important. Proposal: extend
DAV:multistatus by a new child element that indicates (1) the range that was
returned, (2) the total number of results and (3) a URI identifying the
result (for resubmission when getting the "next" results). Such as

<multistatus xmlns='DAV:'>
<search-result>
<href>...identifier for result set...</href>
<total><-- number of results --></total>
<start><-- 1-based index of 1st result --></start>
<length><-- size of result set returned --></length>
<partial-result/><-- indicates that this is a partial result -->
</search-result>
...response elements for search results...
</multistatus>

If a SEARCH request could not be executed or the attempt to execute it resulted in an error, the server MUST indicate the failure with an appropriate status code and SHOULD add a response body as defined in [RFC3253], Section 1.6. Unless otherwise stated, condition elements are empty, however specific conditions element MAY include additional child elements that describe the error condition in more detail.¶

Servers MUST support discovery of the query grammars supported by a search arbiter resource.¶

Clients can determine which query grammars are supported by an arbiter by invoking OPTIONS on the search arbiter. If the resource supports SEARCH, then the DASL response header will appear in the response. The DASL response header lists the supported grammars.¶

The DASL response header indicates server support for a query grammar in the OPTIONS method. The value is a URI that indicates the type of grammar. Note that although the URI can be used to identify each supported search grammar, there is not necessarily a direct relationship between the URI and the XML element name that can be used in XML based SEARCH requests (the element name itself is identified by it's namespace name (a URI reference) and the element's local name).¶

This example shows that the server supports search on the /somefolder resource with the query grammars: DAV:basicsearch, http://foobar.test/syntax1 and http://akuma.test/syntax2. Note that every server MUST support DAV:basicsearch.¶

The DASL response header and the DAV:supported-query-grammar-set property provide means for clients to discover the set of query grammars supported by a resource. This alone is not sufficient information for a client to generate a query. For example, the DAV:basicsearch grammar defines a set of queries consisting of a set of operators applied to a set of properties and values, but the grammar itself does not specify which properties may be used in the query. QSD for the DAV:basicsearch grammar allows a client to discover the set of properties that are searchable, selectable, and sortable. Moreover, although the DAV:basicsearch grammar defines a minimal set of operators, it is possible that a resource might support additional operators in a query. For example, a resource might support a optional operator that can be used to express content-based queries in a proprietary syntax. QSD allows a client to discover these operators and their syntax. The set of discoverable quantities will differ from grammar to grammar, but each grammar can define a means for a client to discover what can be discovered.¶

In general, the schema for a given query grammar depends on both the resource (the arbiter) and the scope. A given resource might have access to one set of properties for one potential scope, and another set for a different scope. For example, consider a server able to search two distinct collections, one holding cooking recipes, the other design documents for nuclear weapons. While both collections might support properties such as author, title, and date, the first might also define properties such as calories and preparation time, while the second defined properties such as yield and applicable patents. Two distinct arbiters indexing the same collection might also have access to different properties. For example, the recipe collection mentioned above might also indexed by a value-added server that also stored the names of chefs who had tested the recipe. Note also that the available query schema might also depend on other factors, such as the identity of the principal conducting the search, but these factors are not exposed in this protocol.¶

Each query grammar supported by DASL defines its own syntax for expressing the possible query schema. A client retrieves the schema for a given query grammar on an arbiter resource with a given scope by invoking the SEARCH method on that arbiter with that grammar and scope and with a root element of DAV:query-schema-discovery rather than DAV:searchrequest.¶

This query grammar supports properties and content, but not conditions
on URL elements (such as the last segment that many WebDAV implementations
treat as "file name"). Discuss possible extension such as adding name
filters to the scope, or adding a specific operator.

DAV:basicsearch uses an extensible XML syntax that allows clients to express search requests that are generally useful for WebDAV scenarios. DASL-extended servers MUST accept this grammar, and MAY accept other grammars.¶

DAV:from defines the query scope. This contains one or more DAV:scope elements. Support for multiple scope elements is optional, however servers MUST fail a request specifying multiple DAV:scope elements if they can't support it (see Section 2.2.2, precondition DAV:search-multiple-scope-supported). The scope element contains mandatory DAV:href and DAV:depth elements.¶

When the scope is a collection, if DAV:depth is "0", the search includes only the collection. When it is "1", the search includes the collection and its immediate children. When it is "infinity", it includes the collection and all its progeny.¶

When the scope is not a collection, the depth is ignored and the search applies just to the resource itself.¶

If the search includes a redirect reference resource (see [RFC4437]), it applies only to that resource, not to its target.

When the child element DAV:include-versions is present, the search scope will include all versions (see [RFC3253], Section 2.2.1) of all version-controlled resources in scope. Servers that do support versioning but do not support the DAV:include-versions feature MUST signal an error if it is used in a query.¶

The DAV:where element defines the search condition for inclusion of resources in the result set. The value of this element is an XML element that defines a search operator that evaluates to one of the Boolean truth values TRUE, FALSE, or UNKNOWN. The search operator contained by DAV:where may itself contain and evaluate additional search operators as operands, which in turn may contain and evaluate additional search operators as operands, etc. recursively.¶

Each operator defined for use in the where clause that returns a Boolean value MUST evaluate to TRUE, FALSE, or UNKNOWN. The resource under scan is included as a member of the result set if and only if the search condition evaluates to TRUE.¶

Consult Appendix A for details on the application of three-valued logic in query expressions.¶

Comparisons of properties that do not have simple types (text-only content) is out-of-scope for the standard operators defined for DAV:basicsearch and therefore is defined to be UNKNOWN (as per Appendix A). For querying the DAV:resourcetype property, see Section 5.13.¶

The example shows a more complex operation involving several operators (DAV:and, DAV:eq, DAV:gt) applied in the criteria. This DAV:where expression matches those resources that are "image/gifs" over 4K in size.¶

The DAV:orderby element specifies the ordering of the result set. It contains one or more DAV:order elements, each of which specifies a comparison between two items in the result set. Informally, a comparison specifies a test that determines whether one resource appears before another in the result set. Comparisons are applied in the order they occur in the DAV:orderby element, earlier comparisons being more significant.¶

The comparisons defined here use only a single property from each resource, compared using the same ordering as the DAV:lt operator (ascending) or DAV:gt operator (descending). If neither direction is specified, the default is DAV:ascending.¶

In the context of the DAV:orderby element, null values are considered to collate before any actual (i.e., non null) value, including strings of zero length (this is compatible with [SQL99]).¶

XPath/XQuery (see draft,
and open issue)
specify string comparisons based on collations, not languages. I think we should
adopt this. This would mean that "xml:lang" would be removed, and an optional
attribute specifying the name of the collation is added.

Comparisons on strings take into account the language defined for that property. Clients MAY specify the language using the xml:lang attribute. If no language is specified either by the client or defined for that property by the server or if a comparison is performed on strings of two different languages, the results are undefined.

The "caseless" attribute may be used to indicate case-sensitivity for comparisons.

Define how comparisons on strings work, esp for i18n.
Need policy statement about sort order in various national languages. (JW said
"non-Latin" but it's an issue even in languages that use the latin char set.)

The DAV:lt, DAV:lte, DAV:gt, and DAV:gte operators provide comparisons on property values, using less-than, less-than or equal, greater-than, and greater-than or equal respectively. The "caseless" attribute may be used with these elements.¶

White space in literal values is significant in comparisons. For consistency with [RFC2518], clients SHOULD NOT specify the attribute "xml:space" (Section 2.10 of [XML]) to override this behaviour.¶

In comparisons, the contents of DAV:literal SHOULD be treated as string, with the following exceptions: ¶

when operand for a comparison with a DAV:getcontentlength property, it SHOULD be treated as an integer value (the behaviour for non-integer values is undefined),

when operand for a comparison with a DAV:creationdate or DAV:getlastmodified property, it SHOULD be treated as a date value in the ISO-8601 subset defined for the DAV:creationdate property ([RFC2518], Section 13.1).

when operand for a comparison with a property for which the type is known, it MAY be treated according to this type.

There are situations in which a client may want to force a comparison not to be string-based (as defined for DAV:literal). In these cases, a typed comparison can be enforced by using DAV:typed-literal instead.¶

<!ELEMENT typed-literal (#PCDATA)>

The data type is specified using the xsi:type attribute defined in [XS1], Section 2.6.1. If the type is not specified, it defaults to "xs:string".¶

1. (insert language defining the comparison following the rules defined in
http://www.w3.org/TR/xpath20/#id-comparisons).
2. Extend Basicsearch QSD grammar to support discovery of typed-literal
3. Update DTD.
4. Discuss behaviour of DAV:literal when the property's type is known
for the complete search scope (is the server allowed to be "smart"?)

will evaluate to TRUE for the resources "/a" and "/b" (their property values can be parsed as type xs:number, and the numerical comparison evaluates to true), to FALSE for "/c" (property value is compatible, but numerical comparison evaluates to false) and UNKNOWN for "/d" and "/e" (the property either is undefined, or its value can not be parsed as xs:number).¶

This operator evaluates to TRUE if the language for the value of the given property is known and matches the language name given in the <literal> element, FALSE if it doesn't match and UNKNOWN if the property itself is not defined.¶

Languages are considered to match if they are the same, or if the language of the property value is a sublanguage of the language specified in the <literal> element (see [XPATH], Section 4.3, "lang function").¶

Rationale: This operator is provided in lieu of defining generic structure queries, which would suffice for this and for many more powerful queries, but seems inappropriate to standardize at this time.¶

The DAV:contains operator is an optional operator that provides content-based search capability. This operator implicitly searches against the text content of a resource, not against content of properties. The DAV:contains operator is intentionally not overly constrained, in order to allow the server to do the best job it can in performing the search.¶

The DAV:contains operator evaluates to a Boolean value. It evaluates to TRUE if the content of the resource satisfies the search. Otherwise, It evaluates to FALSE.¶

Within the DAV:contains XML element, the client provides a phrase: a single word or whitespace delimited sequence of words. Servers MAY ignore punctuation in a phrase. Case-sensitivity is left to the server.¶

The following things may or may not be done as part of the search: Phonetic methods such as "soundex" may or may not be used. Word stemming may or may not be performed. Thesaurus expansion of words may or may not be done. Right or left truncation may or may not be performed. The search may be case insensitive or case sensitive. The word or words may or may not be interpreted as names. Multiple words may or may not be required to be adjacent or "near" each other. Multiple words may or may not be required to occur in the same order. Multiple words may or may not be treated as a phrase. The search may or may not be interpreted as a request to find documents "similar" to the string operand.¶

Servers SHOULD indicate scores for the DAV:contains condition by adding a DAV:score XML element to the DAV:response element. It's value is defined only in the context of a particular query result. The value is a string representing the score, an integer from zero to 10000 inclusive, where a higher value indicates a higher score (e.g. more relevant).¶

Clients should note that, in general, it is not meaningful to compare the numeric values of scores from two different query results unless both were executed by the same underlying search system on the same collection of resources.¶

The DAV:limit XML element contains requested limits from the client to limit the size of the reply or amount of effort expended by the server. The DAV:nresults XML element contains a requested maximum number of DAV:response elements to be returned in the response body. The server MAY disregard this limit. The value of this element is an integer.¶

The DAV:basicsearch grammar defines a search criteria that is a Boolean-valued expression, and allows for an arbitrary set of properties to be included in the result record. The result set may be sorted on a set of property values. Accordingly the DTD for schema discovery for this grammar allows the server to express:¶

the set of properties that may be either searched, returned, or used to sort, and a hint about the data type of such properties

Each instance of a DAV:propdesc element describes the property or properties in the DAV:prop element it contains. All subsequent elements are descriptions that apply to those properties. All descriptions are optional and may appear in any order. Servers SHOULD support all the descriptions defined here, and MAY define others.¶

DASL defines five descriptions. The first, DAV:datatype, provides a hint about the type of the property value, and may be useful to a user interface prompting for a value. The remaining four (DAV:searchable, DAV:selectable, DAV:sortable, and DAV:caseless) identify portions of the query (DAV:where, DAV:select, and DAV:orderby, respectively). If a property has a description for a section, then the server MUST allow the property to be used in that section. These descriptions are optional. If a property does not have such a description, or is not described at all, then the server MAY still allow the property to be used in the corresponding section.¶

This element can be used in place of DAV:prop to describe properties of WebDAV properties not mentioned in any other DAV:prop element. For instance, this can be used to indicate that all other properties are searchable and selectable without giving details about their types (a typical scenario for dead properties).¶

The DAV:datatype element contains a single XML element that provides a hint about the domain of the property, which may be useful to a user interface prompting for a value to be used in a query. Datatypes are identified by an element name. Where appropriate, a server SHOULD use the simple datatypes defined in [XS2].¶

If this element is present, then the server MUST allow this property to appear within a DAV:where element where an operator allows a property. Allowing a search does not mean that the property is guaranteed to be defined on every resource in the scope, it only indicates the server's willingness to check.¶

This element only applies to properties whose data type is "xs:string" and derived data types as per the DAV:datatype property description. Its presence indicates that compares performed for searches, and the comparisons for ordering results on the string property will be caseless (the default is character-by-character).¶

The DAV:operators element describes every optional operator supported in a query. (Mandatory operators are not listed since they are mandatory and permit no variation in syntax.). All optional operators that are supported MUST be listed in the DAV:operators element. The listing for an operator consists of the operator (as an empty element), followed by one element for each operand. The operand MUST be either DAV:operand-property, DAV:operand-literal or DAV:operand-typed-literal, which indicate that the operand in the corresponding position is a property, a literal value or a typed literal value, respectively. If an operator is polymorphic (allows more than one operand syntax) then each permitted syntax MUST be listed separately.¶

This response lists four properties. The datatype of the last three properties is not given, so it defaults to xs:string. All are selectable, and the first three may be searched. All but the last may be used in a sort. Of the optional DAV operators, DAV:is-defined and DAV:like are supported.¶

Note: The schema discovery defined here does not provide for discovery of supported values of the "caseless" attribute. This may require that the reply also list the mandatory operators.¶

This section is provided to detail issues concerning security implications of which DASL applications need to be aware. All of the security considerations of HTTP/1.1 also apply to DASL. In addition, this section will include security risks inherent in searching and retrieval of resource properties and content.¶

A query must not allow one to retrieve information about values or existence of properties that one could not obtain via PROPFIND. (e.g. by use in DAV:orderby, or in expressions on properties.)¶

A server should prepare for denial of service attacks. For example a client may issue a query for which the result set is expensive to calculate or transmit because many resources match or must be evaluated.¶

XML supports a facility known as "external entities", defined in Section 4.2.2 of [XML], which instruct an XML processor to retrieve and perform an inline include of XML located at a particular URI. An external XML entity can be used to append or modify the document type declaration (DTD) associated with an XML document. An external XML entity can also be used to include XML within the content of an XML document. For non-validating XML, such as the XML used in this specification, including an external XML entity is not required by [XML]. However, [XML] does state that an XML processor may, at its discretion, include the external XML entity.¶

External XML entities have no inherent trustworthiness and are subject to all the attacks that are endemic to any HTTP GET request. Furthermore, it is possible for an external XML entity to modify the DTD, and hence affect the final form of an XML document, in the worst case significantly modifying its semantics, or exposing the XML processor to the security risks discussed in [RFC3023]. Therefore, implementers must be aware that external XML entities should be treated as untrustworthy.¶

There is also the scalability risk that would accompany a widely deployed application which made use of external XML entities. In this situation, it is possible that there would be significant numbers of requests for one external XML entity, potentially overloading any server which fields requests for the resource containing the external XML entity.¶

This document is based on prior work on the DASL protocol done by the WebDAV DASL working group until the year 2000 -- namely by Alan Babich, Jim Davis, Rick Henderson, Dale Lowry, Saveen Reddy and Surendra Reddy.¶

ANSI standard three valued logic is undoubtedly the most widely practiced method of dealing with the issues of properties in the search condition not having a value (e.g., being null or not defined) for the resource under scan, and with undefined expressions in the search condition (e.g., division by zero, etc.). Three valued logic works as follows.¶

Undefined expressions are expressions for which the value of the expression is not defined. Undefined expressions are a completely separate concept from the truth value UNKNOWN, which is, in fact, well defined. Property names and literal constants are considered expressions for purposes of this section. If a property in the current resource under scan has not been set to a value, then the value of that property is undefined for the resource under scan. DASL 1.0 has no arithmetic division operator, but if it did, division by zero would be an undefined arithmetic expression.¶

If any subpart of an arithmetic, string, or datetime subexpression is undefined, the whole arithmetic, string, or datetime subexpression is undefined.¶

There are no manifest constants to explicitly represent undefined number, string, or datetime values.¶

Since a Boolean value is ultimately returned by the search condition, arithmetic, string, and datetime expressions are always arguments to other operators. Examples of operators that convert arithmetic, string, and datetime expressions to Boolean values are the six relational operators ("greater than", "less than", "equals", etc.). If either or both operands of a relational operator have undefined values, then the relational operator evaluates to UNKNOWN. Otherwise, the relational operator evaluates to TRUE or FALSE, depending upon the outcome of the comparison.¶

The Boolean operators DAV:and, DAV:or and DAV:not are evaluated according to the following rules:¶

This Section summarizes issues which have been raised during the development of this specification, but for which no resolution could be found with the constraints in place. At the time of this writing, not resolving these issues and publishing as "Experimental" seemed to make more sense than not publishing at all. Future revisions of this specification should revisit these issues, though.

Matching and sorting of textual data relies on collations. With respect to WebDAV SEARCH, a combination of various design approaches could be used:

Require server support for specific collations.

Require that the server can advertise which collations it supports.

Allow a client to select the collation to be used.

In practice, the current implementations of WebDAV SEARCH usually rely on backends they do not control, and for which collation information may not be available. To make things worse, implementations of the DAV:basicsearch grammar frequently need to combine data from multiple underlying stores (such as properties and full text content), and thus collation support may vary based on the operator or property.

Another open issue is what collation formalism to support. At the time of this writing, the two specifications below seem to provide the necessary framework and thus may be the base for future work on collation support in WebDAV SEARCH:

Matching media types using the DAV:getcontenttype property and the DAV:like operator is hard due to DAV:getcontenttype also allowing parameters. A new operator specifically designed for the purpose of matching media types probably would simplify things a lot. See <http://lists.w3.org/Archives/Public/www-webdav-dasl/2003OctDec/0109.html> for a specific proposal.

moved data types before change history rewrote the data types section removed the casesensitive element and replace with the casesensitive attribute added the casesensitive attribute to the DTD for all operations that might work on a string

Jul 20, 1998

A series of changes. See Author's meeting minutes for details.

July 28, 1998

Changes as per author's meeting. QSD uses SEARCH, not PROPFIND. Moved text around to keep concepts nearby. Boolean literals are 1 and 0, not T and F. contains changed to contentspassthrough. Renamed rank to score.

Removed redirection feature, since 301/302 suffices. Removed Query Schema Discovery (former chapter 4). Everyone agrees this is a useful feature, but it is apparently too difficult to define at this time, and it is not essential for DASL.

Removed "xml:space" feature on DAV:literal. Added issue about string comparison vs. collations vs. xml:lang. Updated some of the open issues with details from JimW's original mail in April 1999. Resolved scope vs relative URI references. Resolved issues about DAV:ascending (added to index) and the BNF for DAV:like (changed "octets" to "characters").

Closed open issues regaring the type of search arbiters (JW3) and their discovery (JW9). Rephrased requirements on multistatus response bodies (propstat only if properties were selected, removed requirement for responsedescription).

Close issue "qsd-optional", leave QSD optional. Close issue "2.4-multiple-uris", suggesting that servers should only return one response element per resource in case of multiple bindings. Add and resolve issues "authentication" and "cleanup-iana" (adding the header registration for "DASL"). Re-write rational for using the DAV: namespace, although this is a non-WG submission.

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